1. Field of the Invention
The present invention relates to a microdisk laser with a unidirectional generation property, and more particularly, to a microdisk laser designed in the form of a triangle, wherein the incident angles of portions of a laser beam at two upper sides of the triangle are greater than a critical angle to cause total reflection, so that the laser beam generates with directionality toward the base of the triangle.
2. Description of the Related Art
In recent years, optical integrated circuit techniques have been rapidly developed to integrate optical components for optical switching, operations and the like within a small space such as an IC chip that is an electronic integrated circuit. At this time, a light source is a micro-sized laser that may be utilized in internal integrated circuits and is called “microdisk laser.” The microdisk laser is a kind of semiconductor laser and has a thickness of several micrometers and a laser wavelength including one or two wavelength(s). It is in the form of a disk having the width and height of tens to hundreds of micrometers on a plane and generates omnidirectionally in the plane. Although the microdisk laser has been almost fully developed, a technique for enabling the laser to generate in one direction has not yet been developed. A research on such a technique is one of major researches on the microdisk laser. However, it has been recently found through researches that the directionality of the microdisk laser is associated with the shape thereof.
Heretofore, circular, elliptical and stadium-shaped microdisk lasers and the like have been studied and proposed for optical devices. In a circular laser, a whispering gallery type of beam that omnidirectionally spreads generates, resulting in positive influence on the gain of the laser. However, since the beam spreads omnidirectionally, it has a disadvantage in that the beam is not emitted in one direction. To solve this disadvantage, an elliptical laser has been suggested. Although this laser has improved directionality, a beam thereof also spreads in many directions. This stimulates continuous studies on new models. Recently, a stadium-shaped microdisk with a quantum chaos structure has been suggested. This stadium-shape microdisk has more improved directionality than the elliptical laser and has not yet achieved unidirectionality. Recently, Chern et al. found that a microdisk laser with a spiral structure allows a laser beam to generate in one direction. This spiral laser, however, also has a greater spreading angle and a lot of problems to be solved. FIG. 1 shows the shape and directionality of each of various conventional microdisk lasers. FIGS. 1(a) and (b) show a generation pattern of a circular microdisk laser, FIGS. 1(c) and (d) show a generation pattern of an elliptical microdisk laser, FIG. 1(e) shows a generation pattern of a stadium-shaped microdisk laser, and FIG. 1(f) shows a generation pattern of a spiral microdisk laser.